Structural impact on SARS-CoV-2 spike protein by D614G substitution

Substitution for aspartic acid (D) by glycine (G) at position 614 in the spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appears to facilitate rapid viral spread. The G614 strain and its recent variants are now the dominant circulating forms. Here, we report cryo-electron microscopy structures of a full-length G614 S trimer, which adopts three distinct prefusion conformations that differ primarily by the position of one receptor-binding domain. A loop disordered in the D614 S trimer wedges between domains within a protomer in the G614 spike. This added interaction appears to prevent premature dissociation of the G614 trimer-effectively increasing the number of functional spikes and enhancing infectivity-and to modulate structural rearrangements for membrane fusion. These findings extend our understanding of viral entry and suggest an improved immunogen for vaccine development.

Automated summary

Substitution of aspartic acid (D) with glycine (G) at position 614 in the spike protein of SARS-CoV-2 enhances viral spread. Cryo-electron microscopy structures reveal that the G614 strain has increased infectivity compared to the D614 strain. These findings provide insights for vaccine development and understanding viral entry mechanisms.